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Cisco networking PAT question. Can someone explain the answer?
Refer to the exhibit. A company has an internal network of 172.16.25.0/24 for their employee workstations and a DMZ network of 172.16.12.0/24 to host servers. The company uses NAT when inside hosts connect to outside network. A network administrator issues the show ip nat translations command to check the NAT configurations. Which one of source IPv4 addresses is translated by R1 with PAT?
Pro-inside-global inside-local
10.0.0.17:1025 172.16.12.33:1025
10.0.0.18:1025 172.16.12.35:1025
10.0.0.28:1024 172.16.12.10:1025
10.0.0.28:1025 172.16.12.25:1025
10.0.0.28:1026 172.16.12.35:1025
10.0.0.31:1025 172.16.12.5:1025
answer: 172.16.25.35
Why is this the answer? I m confused. Thank you
1 Answer
- VPLv 72 years ago
I entered this query on Google: diff between nat and pat
Answer:
NAT (Network Address Translation) uses a pool of public addresses that are mapped one-to-one to the private (or "inside") addresses, **keeping the port number intact.**
PAT (Port Address Translation) uses a single outside public address and maps multiple inside addresses to it using **different port numbers.**
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1. So, the sign that something's using NAT is: Different outside IPs, Same Port.
... Example: (Notice the IPs on the left change, but the port is the same...)
... 10.0.0.17:1025 <----- 172.16.12.33:1025
... 10.0.0.18:1025 <----- 172.16.12.35:1025
... 10.0.0.31:1025 <----- 172.16.12.5:1025
2. The sign that something's using PAT is: Same outside IPs, Different Port.
... Example: (Notice the IP on the left DOES NOT change, but the port changes...)
... 10.0.0.28:1024 <----- 172.16.12.10:1025
... 10.0.0.28:1025 <----- 172.16.12.25:1025
... 10.0.0.28:1026 <----- 172.16.12.35:1025
-- edit --
To be honest, I think 172.16.12.10, 12.25, and 12.35 are using PAT.